Cause

Many different water-soluble materials are used in the manufacture of latex emulsion paints. When these paints are applied during hot and humid periods and expected to dry during cool evenings, the painted surface will cool, allowing dew to form. This accumulated moisture on a paint surface whose curing is temporarily delayed will extract and concentrate different water soluble materials from within the paint at the paint surface. As the water evaporates, a concentrated residue is left behind, causing staining, unsightly runs, and gloss patterns.

Solution

Apply paint to all surfaces during climatic conditions that allow proper curing of the paint film. When "surfactant leaching" happens, flush with clean water immediately before the stains have sufficient time to set up or harden. Light scrubbing with a soft brush is acceptable. If stains cannot be removed in this manner, then repainting will be necessary during more favorable weather conditions.

Recommended Sherwin-Williams Coating System

Cause

Stucco and mortar joints contain hydrated or "hot" lime, a dry compound added to improve the workability of these materials. Different mortars are compounded with different amounts of "hot" lime, depending on the end use of the mortar. This problem is then made worse by more "hot" lime being added at the job site.

The alkalinity of mortar, cement mixes, and concrete is expressed numerically by pH readings. The pH of fresh cementious materials is 13 to 14. It takes approximately 30 days for fresh cement materials to drop to an approximate pH of 9. A pH of 9 is less alkaline than a pH of 13, and a coating has a greater assurance of success when applied to a less alkaline surface.

Once these cement walls are cured, the introduction of moisture into these walls will reactivate the high pH alkalinity, resulting in efflorescence, blistering, and peeling of the paint film.

Solution

When damp areas are found on old surfaces, the source of moisture intrusion must be repaired. The surface should then be prepared by removing. chalk, efflorescence, and damaged paint film, and must be thoroughly dry before applying new paint.

Both new and aged unpainted walls must be clean and free of moisture and efflorescence.

Paint products must be chosen with care. The alkalinity of "hot" surfaces will destroy an alkyd or oil product within 6 months. A vinyl acrylic coating will perform slightly better; however, it will ultimately fail. A 100% acrylic coating will give the best service performance.

Flat latex 100% acrylic coatings will perform best because of their ability to allow vapor transmission through the dry paint film. Non-permeable films (e.g, gloss paints) may blister when applied over the same damp condition.

Recommended Sherwin-Williams Coating System

One coat Loxon Exterior Acrylic Masonry Primer

Two coats Loxon Exterior Acrylic Masonry paint.

Cause

The problem appears as a splotchy dirt collection. This discoloration can resemble mildew growth, yet will not change color when washed with household bleach. This problem is not the fault of the paint firm. The non-uniform color is dirt collection that adheres to a component in the hardboard siding. This material migrates to the surface of paints, altering the appearance in a detrimental manner. This foreign material has been identified as a hydrocarbon wax.

Solution

New siding: In severe cases, wax can be felt with he fingers as an oily or waxy substance. Apply a few drops of water to the board surface. If the water beads up and runs off the board, a wax condition is indicated and must be removed.

Repaint old siding: The discoloration can be identified by applying household bleach to rule out possible mildew, tannin, or sulfide staining. Bleaching will occur if these conditions are present. The presence of wax will not be affected by bleach. Follow above directions by applying a few drops of water to establish the presence of wax.

In extreme cases of wax buildup, a clean cloth saturated with mineral spirits or VM&P naptha solvent should be used to remove the deposits. Both rags and VM&P naptha solvent should be changed frequently. An alternative method is to mix one gallon of water with one cup of TSP Substitute and scrub the entire surface with a scrub brush or high-pressure water wash. Rinse thoroughly with plain water. Rescrub areas where water continues to bead up on the surface to that wax deposits are removed. Allow surface to dry thoroughly before applying new coating.

Recommended Sherwin-Williams Coating System

One coat A-100 Alkyd Exterior Wood Primer